Retopology feedback/last steps
To create a good topology I'd stick to retopoflow as it's a huge timesaver for creating a decent topology.
Retopoflow Blendermarket
You can also give it a try for free even if I recommend buying it to support the developers.
Retopoflow Github
However it totally depends on your animation. I think you can even get away with a 50k poly model if you only create instances 'alt + d'.
As soon you want to use deformers on your geometry, it's worth to create a decent topo, otherwise it's getting way to slow. Both your images are rather bad for deformers. (First has to many polygons, second has not uniform quads / clear loops).